Arterial tonometry is a technique that permits the noninvasive monitoring of the pressure within a superficial artery, such as the radial artery at the wrist. The technique is based on an analysis showing that—under the proper conditions—the artery wall does not influence the transmission of arterial pressure to a sensor applied to the skin. Tonometer sensors have been devised that employ various transduction techniques. Perhaps the most advanced sensors include a multiplicity of independent pressure sensors, and are fabricated from silicon. Tonometric measurements have been used to monitor blood pressure during surgery and similar procedures. They have also been used to determine arterial elasticity and pulse wave velocity. Under favorable conditions, the accuracy of tonometric measurements can be described by standard deviations of ∼ 5 mmHg (0.66 kPa).